Electrical cable



(No Model.)

H. O. SPALDING.

ELECTRICAL CABLE. No. 327,491. Patented Sept. 29, 1885.

WITNESSES VENTUR L N. PETERS, Phowrnho n mr, wuningwn, D4 04 UNITEDSTATES PATENT OFFICE.

HENRY O. SPALDING, OF BOSTON, MASSACHUSETTS.

ELECTRICAL CABLE.

E$PECIPICATION forming part of Letters Patent No. 327,491, datedSeptember 29, 1885.

Application filed November 30, 1883. Renewed February 28, 1885. (Nomodel.)

To aZZ whom it may concern:

Be it known that I, HENRY G. SPALDING, a citizen of the United States,and a resident of Boston, in the county of Suffolk and State ofMassachusetts, have invented certain new and useful Improvements inElectric Cables, of which the following is a specification, refer encebeing had-to the drawings accompanying and forming a part of the same.

This invention relates to the construction of electric cables moreparticularly designed for submarine use, the main objects of theinvention being to secure a higher specific insulation and to lessen theretardation to which the electric impulses, by reason of electrostaticinduction, are liable when transmitted through submarine or subterraneanconductors. These objects I attain by the application of insulatingmaterials under certain novel conditions and by the employment ofmetallic screens and strengthening jackets or servings, combined in suchmanner as to pro duce a durable, highly-flexible, and very cheap cable.

In the drawings hereto annexed I have illustrated in its successivestages of manufucture a practicable and efficient form of cableconstructed in accordance with my invention.

In Figure 1, a designates the central conductor, composed, as is usuallythe case, of a number of comparatively fine strands or wires of coppertwisted together. Upon the conductor a is wound spirally a strip ofpaper, I), which has been previously saturated with paraffine. Over thepaper is then applied in any well-known way a coating, 0, of resinousvarnish. Over the coating 0, while still soft, is wound, spirally, asecond strip of paraffined paper d, Fig. 2. Upon this is wound a stripof tin-foil, c, Fig. 3,which is then covered with a coating, f, of theresinous varnish. Next is wound upon the coating f a third strip ofpaper, 9, Fig. 4., which in turn is covered by a spirally-wound strip oftin-foil, h, Fig. 5. This is coated with the resinous varnish, as shownat t, and upon the varnish is wound another strip of paper, 70, Fig. 6.Over the paper It is applied a coating of a bituminous compound, Z, Fig.7 rendered permanently viscous by the addition of some proper substance,and into this coating is wound and embedded a layer of twine, m. For theprotection and strengthening of the cable is then applied the armor a,Fig. 8.

A cable is thus produced composed of layers of plastic, insulating, andfibrous materials and metal, the order of the layers and their specificcharacter being as follows: Paralfined paper surrounding the centralconductor, a resinous coating, a layer of paraffined paper, a layer oftin-foil, a coating of resinous varnish, a layer of paraffined paper, alayer of tin-foil, a coating of resinous varnish, a layer of paraffinedpaper, a bituminous coating, a serving of twine, and thearmor orexterior jacket of wires.

This cable presents certain important advantages due to the materialsenteringinto its composition and the relations in which they are used.

Fibrous materials have heretofore been saturated with paraffine or withresinous compounds and used in the construction of cables. I have found,however, that a fibrous material saturated with paraffine and coatedwith a resinous varnish produces a combination which possesses a muchhigher specific insulation than any of its components. For bringingthese materials into the most efficient relations I use for the fibrousmaterial a strong Manila paper .004 inch in thickness. This is saturatedwith paraffine in the usual way. The varnish or plastic compound that isused in conjunction with this paper is composed wholly or in part of anyresinous substance, though I have obtained the best results from the useof a varnish composed of ninetyparts of shellac and ten parts oflinseed-oil brought to a suitable consistency by the addition ofalcohol. This discovery I take advantage of by applying the coating ofresinous varnish to paraffined paper wherever an insulating layer isneeded in the cable. The resinous varnish may be applied to both sidesof the paper with the result of securing a still higher insulation, andin cases where a paper strip is to be applied over a coating of varnishit is desirable that this be done before the varnish has become hard ordry, as by this means a perfect adherence of the two is effected, thepaper being practically embedded in the coating of varnish.

In forming the several layers on the cable I prefer to wind narrowstrips of paper and of tin-foil spirally around the central core. Thesuccessive layers also should be oppositely wound in order to givegreater strength and flexibility to the cable.

The metal used for the layers may be of various kinds. For the innerlayer ordinary tin-foil will answer. For the layer next to this, or thatdesignated by the letter h, however, it is desirable to use pure tin,since it affords better protection against borers and water, and is noteasily corroded by the mineral substances commonly found in solution inwater.

For the bituminous coating which is applied over the fourth layer ofpaper I use refined Trinidad asphalt, rendered permanently viscous bythe addition of some substance which maintains it in a slightly plasticcondition such as linseedoil or the residuum of the petroleum-still, thelatter being preferable. It results from this that when the serving oftwine is applied it is embedded in the bituminous coating,which, whenwarm, permeates the twine, binding it firmly together and causing ittoadhere closely to the cable.

The insulated metallic sheathings prevent retardation due to theelectrical charges of the earth or the currents set up by induction fromthe central conductor.

In certain respects the construction of the cable may be somewhatvaried-as, for example, in the number or arrangement of the layers; or,as indicated above, important changes may be made in the character ofthe fibrous material or metals used. I have, however, described myinvention in the most practicable and useful form of which I am atpresent aware.

WVhat I therefore claim is 1. An electrical cable having a centralconductor insulated by layers of fibrous material saturated withparaffine and coated with resinous varnish.

2. An electrical cable having a central conductor insulated by one ormore layers of paper saturated with paraffine and coated with a resinoussubstance.

3. An electrical cable having a central conductor insulated by one ormore layers composed of aspirally-wound strip of paper saturated withparaffine and. coated with a resinous substance, as set forth.

4. In an electrical cable, the combination, with an insulating materialcomposed of layers of fibrous material saturated with paraf' fine andcoated with a resinous substance, of a serving of twine wound in aviscous bituminous coating, substantially as set forth.

In witne ss whereof I have hereunto signed my name in the presence oftwo subscribing witnesses.

, H. O. SPALDING.

WVitnesses;

E. B. WELOH, ALEX. L. HAYEs.

